The present invention relates to a method for the application of a scratch protection layer and an antireflection coating system on plastic substrates, in particular, eyeglasses, in that a plasma is produced for the formation of the scratch protection layer, by the plasma CVD method, away from the pertinent plastic substrate, in an excitation gas, and this excitation gas is supplied to the plastic substrate through a tube and a structure-forming gas is introduced, simultaneously, into the vacuum chamber. Furthermore, the invention concerns an apparatus to carry out this method.
An important purpose for such a method is the coating of eyeglasses made of plastic. Such eyeglass are made, for example, of a polycarbonate. Like other plastic substrates, they should not be excessively heated during the coating. Therefore, coating by means of sputtering is problematic and can be used only for the application of relatively thin layers because with longer sputtering processes, the thermal stress of the eyeglasses is too large if expensive cooling of the substrate is not provided.
In order to provide plastic substrates with a relatively thick scratch protection layer, without undesired strong heating of the substrates, a plasma CVD method has been developed in which the plasma is formed, away from the substrate, in an excitation gas, and this excitation gas is supplied to the substrate by a tube in a vacuum chamber, and in which a structure-forming gas is introduced into the vacuum chamber. Such a method is described, for example, in German patent 44 14 083.
Various layers can be applied very economically on a substrate by means of sputtering. As EP 0 699 246 shows, a method is also already known for optical lenses, in which the optical lenses are supplied, one after another, in a passage through several sputtering chambers, and there a layer is applied on the individual lens by sputtering. The thermal stress of the substrates, however, is mostly excessively high with the traditional sputtering for plastic substrates.
A gas flow sputter method for the production of aluminum oxide layers can be found in the journal entitled: Surface and Coatings Technology, 59 (1993), 171-176, in which a sputter electrode with two targets opposite one another is provided, between which a gas flows and subsequently arrives at the substrate. This reference puts particular emphasis on the fact that the thermal stress of the substrate is particularly low with this method.
It is therefore an object of the invention to be able to provide a scratch protection layer and an antireflection coating system that can be carried out so that the treatment can be applied immediately one after another, without an inadmissibly high thermal stress of the plastic substrates occurring.
It is a further object of the present invention to provide an apparatus to carry out this method.